1. Field of the Invention
This invention relates to a temperature control device for cooling high-temperature exhaust gas and a temperature control method for high-temperature exhaust gas.
2. Description of the Related Art
Temperature control devices are generally used to control the high-temperature exhaust gas discharged from a high-temperature gas generation source such as incinerator, melting furnace or the like to a temperature suitable for the treatment with a bag filter, in order to use it as a heat source for boiler in the subsequent step, by a wet treatment by spray of cooling water or using a scrubber. However, flying ash or dust containing a volatile component or molten dust is included in the high-temperature exhaust gas discharged from the incinerator or melting furnace, and the temperature control of such a high-exhaust gas only by cooling water spray causes the problem of the adhesion of the liquefied matter of the volatile component or the solidified matter of the molten dust to the inner wall of a temperature control tower. Further, the wet treatment has a problem in that it is disadvantageous in cost of equipment such as necessity of water treatment equipment because a water-soluble component is contained in the volatile component or molten dust.
In order to prevent the adhesion of the deposit of the inner wall of the temperature control tower, therefore, it is proposed to blow a high-temperature exhaust gas branched from an exhaust gas inlet duct obliquely upward from a purge gas blowing duct in the tangential direction of the circle formed by the horizontal section of the temperature control tower to whirl it as purge gas, or to provide an overflow dam on the upper part within the temperature control tower to fall the water overflowing the overflow dam along the inner wall.
It is also proposed to provide a plurality of high-pressure liquid injection nozzles on the wall of the temperature control tower to blow a high-pressure fluid to the inner wall of the temperature control tower through the high-pressure injection nozzles, thereby removing the adhered dust.
However, since the volatile component or molten dust contained in the high-temperature exhaust gas cannot be sufficiently cooled in the method of blowing and whirling the high-temperature exhaust gas as purge gas, the preventing effect against the adhesion of the volatile component or molten dust to the inner wall of the temperature control tower is not always sufficient. The method of falling water along the inner wall of the temperature control tower requires the water treatment equipment for treating the water-soluble component similarly to the wet treatment. The injection of the high-pressure fluid is only a mere expectant treatment, and it cannot prevent the adhesion of the volatile component or molten dust itself contained in the high-temperature exhaust gas to the inner wall of the temperature control tower.
In the case of an apparatus for incinerating and melting a waste containing metal such as a direct melting furnace of industrial waste, the adhesion of low-melting point materials of alkali metal such as lead (Pb), zinc (Zn), sodium (Na), potassium (K) and the like is more remarkable because they are contained in large quantities. In the technique of obtaining reduced iron by starting from a carbon reducing agent such as coal and an oxidized metal such as iron ore or a waste containing the oxidized metal and performing reduction or reduction and melting at a high temperature of 1000xc2x0 C. or higher, particularly, the cooling of gas and the prevention of adhesion are hardly reconciled because such starting materials contain large quantities of low-melting point materials or volatile components and also generate an extremely high-temperature gas, and an effective temperature control device has not been proposed yet at the present time.
One object of this invention is to provide a temperature control device for effectively preventing the adhesion of a volatile component or molten dust to the inner wall of a temperature control tower and effectively cooling high-temperature exhaust gas, and another object is to provide a temperature control method for high-temperature exhaust gas.
According to this invention, there is provided a temperature control device having a temperature control tower for controlling a blown high-temperature exhaust gas to a proper temperature and discharging the temperature-controlled exhaust gas to the subsequent step side, the temperature control tower comprising a cooling water spray means for spraying cooling water to about the center of the gas flow of the high-temperature exhaust gas and a cooling gas injecting means for injecting a cooling gas along the inner wall of the temperature control device.
The above-mentioned temperature control device further comprises an exhaust gas inlet duct for guiding the high-temperature exhaust gas discharged from a high-temperature gas generating source to the temperature control tower, a gas blowing port provided on the upper part of the temperature control tower so as to communicate with the exhaust gas inlet duct, and a lower discharge duct for discharging the temperature-controlled exhaust gas, wherein the cooling water spray means is constituted so as to spray the cooling water downward to about the center of the gas flow of the high-temperature exhaust gas blown into the temperature control tower, and the cooling gas injecting means is constituted so as to inject the cooling gas downward along the inner wall of the temperature control tower.
In the above-mentioned temperature control device, the cooling gas injecting means is constituted so as to inject the cooling gas downward along the inner wall of the temperature control tower, a plurality of cooling gas injecting means is arranged in the vertical direction of the temperature control tower, the body wall of the temperature control tower has at least two extended step parts extended in diameter toward the lower side, and the cooling gas injecting means are provided on these extended step parts.
In the above-mentioned temperature control device, the cooling gas injecting means is arranged in the direction of injecting the cooling gas obliquely downward to the inner wall of the temperature control tower so that the cooling gas forms a downward whirling gas flow along the inner wall of the temperature control tower.
In the above-mentioned temperature control device, the cooling gas injecting means provided on the two or more extended step parts are constituted so that the cooling gas injecting means provided on the upper extended step part injects the cooling gas in the larger quantity than the cooling gas injecting means provided on the lower extended step part.
The above-mentioned temperature control device further comprises a cooling water injection control means for regulating the injection quantity of the cooling water and a cooling gas injection control means for regulating the injection quantity of the cooling gas, so that the quantity and temperature of the exhaust gas to be discharged with temperature control are constant.
The temperature control device further comprises a cooling water injection control means for regulating the injection quantity of the cooling water and a cooling gas injection control means for regulating the injection quantity of the cooling gas so that the temperature and moisture content of the exhaust gas to be discharged with temperature control are constant.
In the above-mentioned temperature control device, the exhaust gas inlet duct is formed in a reverse V-bent shape between the high-temperature gas generating source and the gas blowing means.
In the above-mentioned temperature control device, the high-temperature gas generating source is a reduced metal manufacturing apparatus for manufacturing reduced iron by starting from a carbon reducing agent such as coal and an oxidized metal such as iron ore or a waste containing the oxidized metal and performing reduction or reduction and melting at a high temperature.
According to this, since the cooling water is injected to about the center of the gas flow of the high-temperature exhaust gas blown into the temperature control tower, and the cooling gas is injected along the inner wall of the temperature control tower, the high-temperature exhaust gas and the volatile component or molted dust are effectively cooled, and the volatile component or molten dust is solidified. The inner wall of the temperature control tower is shielded from the high-temperature exhaust gas by the gas flow of the cooling gas flowing along the inner wall of the temperature control tower without being disturbed by the spray of cooling water. Accordingly, the solidified volatile component or molten dust is not only blown off, even if about to adhered to the inner wall of the temperature control tower, by the gas flow of cooling gas without approaching to the inner wall surface, but also cannot be adhered to the inner wall of the temperature control tower because of its solidification.
The volatile component or molten dust contained in the high-temperature exhaust gas can be cooled more sufficiently than in the structure of blowing and whirling of the high-temperature exhaust gas as purge gas, and an excellent preventing effect against the adhesion to the inner wall of the temperature control tower can be provided. Since the cooling water is evaporated and discharged with the exhaust gas, different from the structure of falling water along the inner wall, the water treatment equipment for treating the water-soluble component is dispensed with. The adhesion of the volatile component or molten dust itself contained in the high-temperature exhaust gas to the inner wall of the temperature control tower as in the injection of a high-pressure fluid can be eliminated.
Since the cooling gas injecting means are provided on the two or more extended step parts provided on the temperature control tower so that the cooling gas forms a downward whirling gas flow along the inner wall of the temperature control tower, the inner wall of the temperature control tower can be widely covered with the gas flow of the cooling gas to effectively prevent the direct contact with the high-temperature exhaust gas.
Since the cooling gas injecting means provided on the upper extended step part injects the cooling gas in the larger quantity than the cooling gas injection means provided on the lower extended step part, the inner wall near the gas blowing port of the temperature control tower is covered with a large quantity of the cooling gas flow, so that a large quantity of the volatile component or molten dust contained in the high-temperature exhaust gas just after blowing, even if solidified, can be effectively prevented from being adhered to the inner wall near the gas blowing port of the temperature control tower.
Further, since the quantity and temperature of the exhaust gas discharged with temperature control are controlled so as to be constant, the exhaust gas can be properly discharged without readily increasing the exhaust gas quantity in addition to the stable treatment of exhaust gas in the subsequent step, the enlargement of the apparatus on the subsequent step side can be prevented.
Since the temperature and moisture content of the exhaust gas to be discharged with temperature control are controlled so as to be constant, the adhesion of the flying ash or dust component to a duct or heat exchanger in the subsequent step or the corrosion by acid thereof can be prevented in addition of the stable treatment of the exhaust gas in the subsequent step.
Since the inertial force of the high-temperature exhaust gas is suppressed by the bent part of the exhaust gas inlet duct to prevent the drift in the blowing through the gas blowing port of the temperature control tower, the disturbance of the gas flow of the cooling gas flowing along the inner wall of the temperature control tower can be prevented without deteriorating the cooling effect within the temperature control device.
Although the high-temperature exhaust gas discharged from the reduced metal manufacturing apparatus contains a large quantity of volatile or molten dust component, such a high-temperature exhaust gas can be also temperature-controlled while effectively cooling and solidifying the volatile or molten dust component by spray of cooling water and injection of cooling water and also preventing the adhesion of a large quantity of the solidified volatile or molten dust component to the inner wall of the temperature control tower.
According to this invention, further, there is provided a temperature control method for high-temperature exhaust gas comprising blowing a high-temperature exhaust gas discharged from a high-temperature gas generating source to a temperature control tower from a gas blowing port provided in the upper part thereof through an exhaust gas inlet duct, temperature-controlling the blown high-temperature exhaust gas to a proper temperature, and discharging it to the subsequent step side through a lower discharge duct, wherein cooling water is sprayed from the upper part of the temperature control tower to about the center of the gas flow of the high-temperature exhaust gas, and cooling gas is injected obliquely downward so as to form a whirling gas flow along the inner wall of the temperature control tower.
In the above-mentioned temperature control method for high-temperature exhaust gas, the temperature control tower comprises two or more extended step parts extended in diameter toward the lower side, the cooling gas is injected obliquely down so as to form a whirling gas flow along the inner wall of temperature control tower in the larger quantity from the cooling gas injecting means provided on the upper extended step part than from the cooling gas injection means provided on the lower side, the injection quantity of the cooling gas and the spray quantity of the cooling water are regulated so that the quantity and temperature of the exhaust gas discharged with temperature control through the lower discharge duct are constant, and the injection quantity of the cooling gas and the spray quantity of the cooling water are regulated so that the temperature and moisture content of the exhaust gas temperature discharged with temperature control through the lower discharge duct are constant.
In the above-mentioned temperature control method for high-temperature exhaust gas, the high-temperature exhaust gas discharged from the high-temperature generating source to the temperature control tower through the gas blowing port is once ascended obliquely and then descended obliquely in the blowing.
In the above-mentioned temperature control method for high-temperature exhaust gas, the high-temperature exhaust gas discharged from the high-temperature gas generating source, which is a reduced metal manufacturing apparatus for manufacturing reduced iron by starting from a carbon reducing agent such as coal and an oxidized metal such as iron ore or a waste containing the oxidized metal and performing reduction or reduction and melting at a high temperature, to the temperature control tower through the gas blowing port.
According to this, since the cooling water is sprayed to about the center of the gas flow of the high-temperature exhaust gas blown into the temperature control tower, and the cooling gas is injected along the inner wall of the temperature control tower, the high-temperature exhaust gas and the volatile or molten dust component are effectively cooled, and the volatile or molten dust component is solidified. The inner wall of the temperature control tower is shielded from the high-temperature exhaust bas by the gas flow of the cooling gas flowing along the inner wall of the temperature control tower without being disturbed by the spray of cooling water. Accordingly, the solidified volatile or molten dust component is not only blown off, even if about to adhere to the inner wall of the temperature control tower, by the gas flow of the cooling gas without approaching to the inner wall surface, but also cannot be adhered to the inner wall of the temperature control tower because of its solidification.
The volatile component or molten dust contained in the high-temperature exhaust gas can be cooled more sufficiently than in the structure of blowing and whirling the high-temperature exhaust gas as purge gas, and an excellent preventing effect against the adhesion to the inner wall of the temperature control tower can be provided. Since the cooling water is evaporated and discharged with the exhaust gas, different from the structure of falling water along the inner wall, the water treatment equipment for treating the water-soluble component is dispensed with. The adhesion of the volatile component or molten dust itself contained in the high-temperature exhaust gas to the inner wall of the temperature control tower as in the injection of a high-pressure fluid can be eliminated.
Since the quantity and temperature of the exhaust gas to be discharged with temperature control are controlled so as to be constant, the exhaust gas can be properly discharged without readily increasing the exhaust gas quantity in addition to the stable treatment of exhaust gas in the subsequent step, and the enlargement of the subsequent step-side apparatus can be prevented.
Since the temperature and moisture content of the exhaust gas to be discharged with temperature control are controlled so as to be constant, the adhesion of flying ash or dust component to a duct or heat exchange or the corrosion by acid thereof in the subsequent step can be prevented in addition to the stable treatment of the exhaust gas in the subsequent step.
Since the inertial force of the high-temperature exhaust gas is suppressed by the bent part of the exhaust gas inlet duct to prevent the drift in the blowing from the gas blowing port of the temperature control tower, the disturbance of the gas flow of the cooling gas flowing along the inner wall of the temperature control tower can be prevented without deteriorating the cooling effect within the temperature control device.
Although the high-temperature exhaust gas discharged from the reduced metal manufacturing apparatus contains a large quantity of volatile or molten dust component, such a high-temperature exhaust gas can be also temperature-controlled while effectively cooling and solidifying the volatile or molten dust component by spray of cooling water and injection of cooling gas and preventing the adhesion of the solidified volatile or molten dust component to the inner wall of the temperature control tower.